We had a minor domestic disaster this morning. It's not unusual. With four children, there's always some kind of crisis. Today, I followed a trail of water along the floor to my youngest daughter. She was shaking her "sippy cup" upside down, depositing a full cup of water on the carpet... and on my new digital grand piano.
Since the entire purpose of the "sippy cup" is to contain the water, not to spread it around this house, this was perplexing.
On investigation, I found that this failure in function actually mimicked common dynamics of major disasters. In Inviting Disaster, James R. Chiles describes numerous mechanical and industrial disasters, each with a terrible cost in lives. In Release It, I discuss software failures that cost millions of dollars---though, thankfully, no lives. None of these failures come as a bolt from the blue. Rather, each one has precursor incidents: small issues whose significance are only obvious in retrospect. Most of these chains of events also involve humans and human interaction with the technological environment.
The proximate cause of this morning's problem was inside the sippy cup itself. The removable valve was inserted into the lid backwards, completely negating its purpose. A few weeks earlier, I had pulled a sippy cup from the cupboard with a similarly backward valve. I knew it had been assembled by my oldest, who has the job of emptying the dishwasher, so I made a mental note to provide some additional instruction. Of course, mental notes are only worth the paper they're written on. I never did get around to speaking with her about it.
Today, my wonderful mother-in-law, who is visiting for the holidays, filled the cup and gave it to my youngest child. My mother-in-law, not having dealt with thousands of sippy cup fillings, as I have, did not notice the reversed valve, or did not catch its significance.
My small-scale mess was much easier to clean up than the disasters in "Release It!" or "Inviting Disaster". It shared some similar features, though. The individual with experience and knowledge to avert the problem--me--was not present at the crucial moment. The preconditions were created by someone who did not recognize the potential significance of her actions. The last person who could have stopped the chain of events did not have the experience to catch and stop the problem. Change any one of those factors and the crisis would not have occurred.